RESUMO
The Institute of Medicine updated guidelines for gestational weight gain in 2009, with no special recommendations for gestational diabetes. Our objectives were to describe the prevalence of weight gain adequacy and their association with adverse pregnancy outcomes in gestational diabetes. We searched MEDLINE, EMBASE, COCHRANE and SCOPUS. We calculated the pooled prevalence of gain adequacy and relative risks for pregnancy outcomes within Institute of Medicine categories. Thirty-three studies/abstracts (88,599 women) were included. Thirty-one studies provided data on the prevalence of weight gain adequacy; it was adequate in 34% (95% CI: 29-39%) of women, insufficient in 30% (95% CI: 27-34%) and excessive in 37% (95% CI: 33-41%). Excessive gain was associated with increased risks of pharmacological treatment, hypertensive disorders of pregnancy, caesarean section, large for gestational age and macrosomic babies, compared to adequate or non-excessive gain. Weight gain below the guidance had a protective effect on large babies (RR: 0.71; 95% CI: 0.56-0.90) and macrosomia (RR 0.57; 95% CI 0.40-0.83), and did not increase the risk of small babies (RR 1.40; 95% CI 0.86-2.27). Less than recommended weight gain would be beneficial, while effective prevention of excessive gain is of utmost importance, in gestational diabetes pregnancies. Nevertheless, no ideal range for weight gain could be established.